Decibel

A decibel (dB) is a unit of measurement that came from the need to describe the efficiency of telephone circuits. It would replace "transmission units" which were from the telegraph days. It was decided that they wanted to use a name that connected to the inventor of the telephone, Alexander Graham Bell and created the unit of a "bel." The bel is seldom used, as the decibel was the proposed working unit.  "Deci" denote one-tenth of the "bel" measurement. The new measurement was proposed in 1924 by the Bell Telephone Laboratories. 

In a non-technical sense, most people just think of a decibel as a way to measure the loudness of a sound. Breathing is 10 decibels; conversations in a restaurant is about 60; a motorcycle at 25 ft is 90 dB; live rock music is about 108 - 114 dB.

Bell at the opening of the long-distance line from New York to Chicago, 1892 Link